1. Technical Field
The present invention relates to a resonator element, a resonator, a resonator device, an oscillator, an electronic apparatus, and a moving object.
2. Related Art
In the related art, resonator elements using quartz crystal are known. Such resonator elements are widely used for reference frequency sources or oscillation sources of various electronic apparatuses since frequency-temperature characteristics are excellent. In particular, the resonator elements using quartz crystal substrates cut at cut angles called AT-cut are widely used for mobile communication apparatuses such as mobile phones since the frequency-temperature characteristics represent cubic curves.
For example, JP-A-2005-94410 discloses that the middle portions of convex portions are deviated in a direction distant from pad electrodes from the middle portions of a piezoelectric substrate in a resonator element with a mesa structure in which the convex portions are formed on both main surfaces of the piezoelectric substrate. Such a resonator element is mounted on a package, for example, by bonding the pad electrodes to a package base by a conductive bonding material.
However, in the foregoing resonator element, hysteresis sometimes occurs in frequency-temperature characteristics of the resonator element due to stress of the bonding material.
Further, in the foregoing resonator element, it is desirable to reduce equivalent series resistance (Crystal Impedance (CI) value).